d: Fix internal compiler error: Segmentation fault at gimple-expr.cc:88

Because complex types are deprecated in the language, the new way to
expose native complex types is by defining an enum with a basetype of a
library-defined struct that is implicitly treated as-if it is native.
As casts are not implicitly added by the front-end when downcasting from
enum to its underlying type, we must insert an explicit cast during the
code generation pass.

	PR d/106623

gcc/d/ChangeLog:

	* d-codegen.cc (underlying_complex_expr): New function.
	(d_build_call): Handle passing native complex objects as the
	library-defined equivalent.
	* d-tree.h (underlying_complex_expr): Declare.
	* expr.cc (ExprVisitor::visit (DotVarExp *)): Call
	underlying_complex_expr instead of build_vconvert.

gcc/testsuite/ChangeLog:

	* gdc.dg/torture/pr106623.d: New test.

1 files changed, 28 insertions, 0 deletions

diff --git a/gcc/testsuite/gdc.dg/torture/pr106623.d b/gcc/testsuite/gdc.dg/torture/pr106623.d
new file mode 100644
index 0000000..d782b23
--- /dev/null
+++ b/gcc/testsuite/gdc.dg/torture/pr106623.d
@@ -0,0 +1,28 @@
+// https://gcc.gnu.org/bugzilla/show_bug.cgi?id=106623
+// { dg-do compile }
+private struct _Complex(T) { T re; T im; }
+enum __c_complex_double : _Complex!double;
+
+pragma(inline, true)
+ulong hashOf()(scope const double val)
+{
+    return *cast(ulong*)&val;
+}
+
+pragma(inline, true)
+ulong hashOf()(scope const _Complex!double val, ulong seed = 0)
+{
+    return hashOf(val.re) + hashOf(val.im);
+}
+
+pragma(inline, true)
+ulong hashOf()(__c_complex_double val, ulong seed = 0)
+{
+    return hashOf(cast(_Complex!double) val, seed);
+}
+
+ulong test106623()
+{
+    __c_complex_double val;
+    return hashOf(val);
+}